Pisidium amnicum is a species of very small freshwater clam, sometimes known as the greater European peaclam or the River pea shell. It is an aquatic bivalve in the family Sphaeriidae.

Description

Although only 9 mm (range 7–11 mm) in length, this species is considerably larger than most Pisidium species, and has a fairly thick, concentrically ridged shell. Its shell is solid, glossy, triangular-oval in shape, and has broad but not prominent umbos often coated with a dull ferruginous deposit. Its colour is grey-white to brown, often with a greenish cast.

Distribution

Its native distribution is Palearctic. The species has been introduced to northeastern North America.

• Czech Republic – endangered (EN), endangered in Bohemia (EN), critically endangered in Moravia
• Slovakia
• Germany – highly endangered (Stark gefährdet)
• Nordic countries: Denmark, Finland, Iceland, Norway and Sweden (not in the Faroe Islands)
• Great Britain and Ireland

Ecology

In Europe, it requires clean water and high levels of calcium.